The patent WO2013020993 A1 disclosed synthetic approaches to obtain compound of formula (I). However, according to the synthetic approach in patent WO2013020993 A1, deprotection of one of the intermediates, 3-(aminomethyl)-N,N-dibenzyl-oxetan-3-amine, for synthesizing compound of formula (I) by hydrogenation with palladium on carbon will lead to heavy metal residual issue, which is not suitable for process chemistry and large scale manufacture. In addition, another intermediate, tert-butyl [(3-aminooxetan-3-yl)methyl] carbamate, for synthesizing compound of formula (I) suffers from instability as the primary amine.
In this invention, a simple and effective synthetic approach is developed to synthesize compounds of formula (I). This synthetic approach can be applied on technical scale and allows to obtain the product in a good yield, desired purity and stable form without using heavy metal catalyst.